1. Field of the Invention
The present invention relates to a working vehicle including a hydraulic pump unit operatively driven by a driving source, and a hydraulic motor unit spaced apart from the hydraulic pump unit, the hydraulic pump unit and the hydraulic motor unit being fluidly connected to each other so as to form a traveling system HST.
2. Background Art
The working vehicle including a hydraulic pump unit operatively and rotatably driven by a driving power source, and a hydraulic motor unit spaced apart from the hydraulic pump unit so as to be arranged in proximity to a corresponding driving wheel, and configured to drive the driving wheel with variable speeds by means of a traveling system HST formed by the hydraulic pump main body of the hydraulic pump unit and the hydraulic motor main body of the hydraulic motor unit is conventionally known (see e.g., Japanese Laid-Open Patent Publication No. 2003-291674).
The thus configured working vehicle includes a working vehicle of a wheel motor type in which the hydraulic motor unit is provided for each driving wheel, a working vehicle of a mechanical differential type in which an output of the hydraulic motor unit is differentially transmitted to a pair of right and left driving wheels via a mechanical differential gear device, and a working vehicle of a hydraulic differential type in which a pair of hydraulic motor main bodies corresponding to the pair of right and left driving wheels are fluidly connected to each other via a pair of motor-side operation fluid lines and a hydraulic pump main body is fluidly connected to the pair of motor-side operation lines via a pair of operation fluid lines.
The working vehicle could enhance the degree of freedom in design in comparison with the working vehicle in which the hydraulic pump unit and the hydraulic motor unit are integrated to each other, since the hydraulic motor unit is arranged in proximity to the corresponding driving wheel while being spaced apart from the cooperating hydraulic pump unit.
However, cooling of the hydraulic motor unit is not sufficiently taken into consideration in the conventional working vehicle in which the hydraulic pump unit and the hydraulic motor unit are disposed away from each other.
That is, the hydraulic motor main body is rotatably driven by the hydraulic fluid pressure from the hydraulic pump main body. In this operation, the temperature of the hydraulic pump main body and the hydraulic motor main body rises due to the influence of friction and the like.
The rise in temperature of the hydraulic motor main body causes rise in temperature and the like of the HST hydraulic fluid, resulting in worsening the transmission efficiency of the HST.
Similarly, cooling of the hydraulic pump unit is not sufficiently taken into consideration in the conventional working vehicle.
The rise in temperature of the hydraulic pump main body also causes rise in temperature and the like of the HST hydraulic fluid, resulting in worsening the transmission efficiency of the HST.
In view of the conventional art, it is an object of the present invention to provide a working vehicle including a hydraulic pump unit operatively and rotatably driven by the driving power source and a hydraulic motor unit spaced apart from the hydraulic pump unit, where the cooling efficiency of the hydraulic motor unit could be enhanced.
Another object of the present invention is to also enhance the cooling efficiency of the hydraulic pump unit in the working vehicle of the above type.
Still another object of the present invention is to provide a working vehicle including a hydraulic pump unit operatively and rotatably driven by the driving power source, and a hydraulic motor unit spaced apart from the hydraulic pump unit, the hydraulic pump unit including a PTO clutch mechanism operatively and rotatably driven by the driving power source, where the cooling efficiency of the hydraulic motor unit and the PTO clutch mechanism could be enhanced.